Springmount farmer Rod Taylor said he had three paddocks with turnips as big as 28cm by 20cm thick.

"Anybody I've told doesn't believe it until you pull them out of the bag,'' Mr Taylor said.

"My wife tells people we've got turnips as big as Rod's head.''

The turnips were keeping his 66 sheep going because the grass in the paddocks had suffered due to the hot weather and no rain, he said.

"The sheep wander into the paddocks when they want a good feed of turnips and then wander away to eat grass again,'' Mr Taylor said.

He said the over-sized turnips had been grown without water or fertilizer, and they had been a month late sowing them.

Mr Taylor and his wife Margaret have been at the property for 25 years and grew the turnips with fowl manure, lime and by deep ripping the soil, he said.

He said the company where he had first purchased the seeds in Ballarat was shocked by the size of them.

"They said I've seen some turnips but that is ridiculous," Mr Taylor said.